Behavior counters for improved JUnit tests

InvokeCounter.java

package com.octodecillion.junit;

import static org.hamcrest.core.IsEqual.equalTo;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;

import java.util.HashMap;
import java.util.Map;

/**
 * Counters to assert block execution in JUnit tests.
 * 
 * @author jbetancourt
 * @since 2012-11-19T20:52-05
 */
public class InvokeCounter {
	private final Map<String, Integer> counters = new HashMap<String, Integer>();
	private static final String DEFAULT_COUNTER = "DEFAULT__COUNTER";
	private static Integer ZERO = Integer.valueOf(0);

	{
		counters.put(DEFAULT_COUNTER, ZERO);
	}

	public int get() {
		return get(DEFAULT_COUNTER);
	}

	public void increment() {
		incrementValue(DEFAULT_COUNTER);
	}

	public void increment(int shouldBe) {
		increment(DEFAULT_COUNTER, shouldBe);
	}

	public void reset() {
		counters.put(DEFAULT_COUNTER, ZERO);
	}

	@SuppressWarnings("boxing")
	public void assertCounter(int shouldBe) {
		Integer value = counters.get(DEFAULT_COUNTER);
		assertThat(NOT_WHERE_IT_SHOULD_BE, value, equalTo(shouldBe));
	}

	@SuppressWarnings("boxing")
	public void assertCounterMin(int shouldBe) {
		Integer value = counters.get(DEFAULT_COUNTER);
		assertTrue(NOT_AT_LEAST_MINIMUM + shouldBe + "'", value >= shouldBe);
	}

	@SuppressWarnings("boxing")
	public void assertCounterMax(int shouldBe) {
		Integer value = counters.get(DEFAULT_COUNTER);
		assertTrue(NOT_AT_LEAST_MAXIMUM + shouldBe + "'", value <= shouldBe);
	}

	public void create(String name) {
		if (name == null) {
			throw new NullPointerException(NAME_IS_NULL);
		}

		if (name.trim().length() == 0) {
			throw new IllegalArgumentException(NAME_IS_BLANK);
		}

		if (counters.containsKey(name)) {
			throw new IllegalStateException(
					String.format(ALREADY_CREATED, name));
		}

		counters.put(name, ZERO);
	}

	@SuppressWarnings("boxing")
	public int get(String name) {
		return counters.get(name);
	}

	public void increment(String name) {
		incrementValue(name);
	}

	public void reset(String name) {
		counters.put(name, ZERO);
	}

	@SuppressWarnings("boxing")
	public void increment(String name, int shouldBe) {
		Integer value = incrementValue(name);
		assertThat(NOT_INCREMENTED_CORRECTLY, value, equalTo(shouldBe));
	}

	@SuppressWarnings("boxing")
	public void assertCounter(String name, int shouldBe) {
		Integer value = counters.get(name);
		assertThat(NOT_WHERE_IT_SHOULD_BE, value, equalTo(shouldBe));
	}

	@SuppressWarnings("boxing")
	public void assertCounterMin(String name, int shouldBe) {
		Integer value = counters.get(name);
		assertTrue(NOT_AT_LEAST_MINIMUM + shouldBe + "'", value >= shouldBe);
	}

	@SuppressWarnings("boxing")
	public void assertCounterMax(String name, int shouldBe) {
		Integer value = counters.get(name);
		assertTrue(NOT_AT_LEAST_MINIMUM + shouldBe + "'", value <= shouldBe);
	}

	@SuppressWarnings("boxing")
	private Integer incrementValue(String name) {
		if (name == null || name.trim().length() == 0) {
			throw new NullPointerException(INCREMENT_NAME_IS_NULL_OR_BLANK);
		}

		if (!counters.containsKey(name)) {
			throw new IllegalStateException(String.format(NOT_FOUND, name));
		}

		Integer value = counters.get(name);
		value++;
		counters.put(name, value);

		return value;
	}

	private static final String ALREADY_CREATED = "Counter '%s' already created";
	private static final String NAME_IS_NULL = "counter, create, name is null";
	private static final String NAME_IS_BLANK = "counter, create, name is empty";
	private static final String NOT_FOUND = "Counter '%s' not found";
	private static final String NOT_INCREMENTED_CORRECTLY = "counter was not incremented correctly";
	private static final String INCREMENT_NAME_IS_NULL_OR_BLANK = "counter, increment, name is null or blank";
	private static final String NOT_AT_LEAST_MINIMUM = "counter is not at least minimum '";
	private static final String NOT_AT_LEAST_MAXIMUM = "counter is not at least maximum '";
	private static final String NOT_WHERE_IT_SHOULD_BE = "counter is not where it should be";
}

Source code to accompany blog post: http://octodecillion.com/blog/behavior-counts-improve-junit/